I ate McDonalds for lunch quite often when I was working. I have zero health issues as of last month's checkup, and I was still losing weight till the day I got laid off.

If you arent a lazy ass and dont eat there breakfast, lunch, and dinner, its not going to hurt you.

I bet your liver lipids are elevated (which they won't pick up on a standard exam). You are setting yourself up for liver disease, type 2 diabetes, and cardiovascular disease. But as long as you weight stays off I guess you are good...